Submission #8001475

---

Source Code Expand

N = int(input().strip())
A = list(map(int, input().strip().split(' ')))
if N % 2 == 1:
  checklist = {0:1}
  for i in range((N-1)//2):
    checklist[(i+1)*2] = 2
else:
  checklist = {(i*2+1):2 for i in range(N//2)}

for a in A:
  if a in checklist and checklist[a] in {1,2}:
    checklist[a] -= 1
  else:
    print(0)
    exit()
print(int(2**(N//2))%1000000007)

Submission Info

Judge Result